Mercedes-Benz is reportedly facing a class-action lawsuit in the U.S. District Court of New Jersey for alleged defects in the company's M156 V8. According to the plaintiffs, premature internal wear occurs because the engine uses cast nodular iron camshafts and 9310-grade steel valves. Something about that combination causes early failure, either due to improper offset of the components or inadequate heat treating. The plaintiffs also allege that Mercedes-Benz and AMG have known about the issue since 2007, when Daimler released a service bulletin on the problem. At this point, it's unclear how many engines this alleged defect covers, or exactly when or if the lawsuit will go to trial.
The M156 V8 – one of the snarliest and best-sounding engines we've ever driven – has served as the powerhouse for a wide range of AMG vehicles. The 6.3-liter lump actually displaces 6.2 liters, but churns out 525 horsepower in its newest iteration. The engine has found its way into vehicles like the C63 AMG, E63 AMG, ML63 AMG and SL63 AMG, among others. Head over to BenzBoost for a look at the full lawsuit.